Method of making hollow concrete panels

ABSTRACT

A method of making hollow concrete panels comprising pouring a lower concrete layer, placing thereon a hollow mold core including a top wall and side walls and an open bottom defined by edges, said top wall having side edges and a center line, sealing along said bottom edges by placing gaskets along said bottom edges and pouring concrete on top of the core to press the gaskets against the bottom to prevent fresh concrete from entering said open bottom and locking the core in place, pouring an upper concrete layer connecting with said lower layer, peeling the side and top walls of the core from the concrete after it has set and collapsing the core, said side walls being first peeled from the bottom up and then the top wall being peeled starting at the top wall side edges and progressing toward the center line of the top wall, and removing the core from the concrete.

United States Patent Glass 9 [54] METHOD OF MAKING HOLLOW CONCRETE PANELS [72] Inventor: John P. Glass, 79 La Grange Ave.,

Essington, Pa. 19029 [22] Filed: Oct. 14, 1966 [21] Appl. No.: 600,300

Related US. Application Data [60] Division of Ser. No. 166,566, Jan. 16, 1962, Pat. No. 3,213,512, and a continuation of Ser. No. 382,910, July 15, 1964, abandoned.

[52] US. Cl. ..264/71, 264/34, 264/308, 264/334 [51] Int. Cl. ..B28b 21/18 [58] Field of Search ..264/34, 71, 308, 314, 334; 25/131 H, 128

[56] References Cited UNITED STATES PATENTS 857,581 6/1907 Boyle .....264/314 FOREIGN PATENTS OR APPLICATIONS 601,667 5/1948 Great Britain ..25/131 H [451 Sept. 26, 1972 587,255 4/1947 Great Britain ..25/128 Primary Examiner-Robert F. White Assistant Examiner-Allen M. Sokal AttorneyJ0hn F. A. Earley [5 7] ABSTRACT A method of making hollow concrete panels comprising pouring a lower concrete layer, placing thereon a hollow mold core including a top wall and side walls and an open bottom defined by edges, said top wall having side edges and a center line, sealing along said bottom edges by placing gaskets along said bottom edges and pouring concrete on top of the core to press the gaskets against the bottom to prevent fresh concrete from entering said open bottom and locking the core in place, pouring an upper concrete layer connecting with said lower layer, peeling the side and top walls of the core from the concrete after it has set and collapsing the core, said side walls being first peeled from the bottom up and then the top wall being peeled starting at the top wall side edges and progressing toward the center line of the top wall, and removing the core from the concrete.

5 Claims, 10 Drawing Figures PAn-iminsmwn 3.694.531

SHEET? 0F 3 FIG.

JNVENTOR.

JOHN P. GLASS ATTORNEY METHOD OF MAKING HOLLOW CONCRETE PANELS This invention relates to concrete panels and more particularly concerns a method for making them. This application is a division of my patent application Ser. No. 166,566, filed Jan. 16, 1962, now US. Pat. No. 3,213,512 which issued Oct. 26, 1965, and is a continuation of my patent application Ser. No. 382,910, filed July 15, 1964, now abandoned.

Hollow concrete panels are useful in the building industry, the hollow chambers forming ducts for ventilation and for the passage of other equipment such as electrical wiring or the like.

A conventional method of forming hollow concrete panels comprises the steps of positioning mold cores in a concrete mold, then pouring the concrete over and under the cores. This method presents difficulties. For example, it cannot be ascertained whether or not the concrete below the mold cores is free of voids, since visual inspection is impossible. Also, the liquid concrete as it is poured tends to float and mold cores upwardly because of the hydraulic pressures caused by the concrete that is between and underneath the cores. To prevent the cores from floating and shifting, it has heretofore been proposed to construct elaborate superstructures which have for their only function the keeping of the mold cores in position during the manufacturing of concrete panels. Such superstructures are expensive, and have the further disadvantage of impeding the movement of the workers engaged in manufacturing the panels.

Conventional mold cores have usually consisted of flexible inflatable tubes, or rigid expendable tubes, or collapsible forms which may be round 'or rectangular in cross-section. Such mold cores presented difficulty during the process of manufacturing the hollow concrete panels because of their buoyancy in liquid concrete,because ofthe expense of leaving cores in the concrete, and because of the difficulty in collapsing cores which are to be removed from the completed concrete panel.

Accordingly, it is an object of this invention to overcome the aforementioned difficulties of the prior art. It is another object of this invention to provide a collapsible mold core which may readily be placed in position before the concrete is poured, may easily be held in such position during the pouring of the concrete, and may easily be removed from the concrete panel after the concrete has cured.

It is another object of this invention to eliminate the need for the superstructures previously necessary for keeping the mold coresin place during the manufacturing operation.

. It is another object of this invention to provide a method and apparatus for manufacturing reinforced concrete hollow panels of large size, for example, 40 by 60 feet and weighing 50 tons or so.

, It is another object of this invention to provide a collapsible mold core which separates from the concrete easily, even though the length of the core may be considerable, for example, 60 feet.

It is another object of this invention to provide a method and apparatus for making hollow concrete forms wherein a collapsible mold core peels away from the concrete, rather than pulling or tearing, and the mold core is collapsed in progressive stages in order to obtain this peeling motion.

Other objects and advantages of this invention, including its simplicity and economy, as well as the ease with which it may be adapted to existing equipment, will further become apparent hereinafter and in the drawings, in which:

FIG. 1 is a fragmentary view in perspective of a concrete mold apparatus constructed in accordance with the invention;

FIG. 2 is a view in cross-section of a mold core and illustrates the mold core in open position, ready to be placed on a bottom layer of concrete;

FIG. 3 is a view similar to FIG. 2 showing the mold core in place at a later stage of operation with an upper layer of concrete having been poured so that the mold core is now imbedded in the concrete;

FIG. 4 is a view similar to FIG. 3 showing a later stage of operation with the concrete having stiffened and the side wall units of the mold core having been retracted away from the concrete;

FIG. 5 is a view similar to FIG. 4 showing a later stage in operation with the top walls of the mold form also having been withdrawn from contact with the concrete;

FIG. 6 is a fragmentary view in perspective showing the construction of the side wall unit of the mold core;

FIG. 7 is a fragmentary view in perspective show the construction of the top wall unit of the mold core;

FIG. 8 is a view in perspective of another embodiment of a mold core constructed in accordance with the present invention;

FIG. 9 is a view in cross-section of the mold core of FIG. 8 shown positioned on a lower layer of concrete; and

FIG. 10 is a view similar to FIG. 9 at a later stage of operation showing the mold core with its side and top walls withdrawn from the concrete.

Although specific terms are used in the following description for clarity, these terms are intended to refer only to the structure shown in the drawings and are not intended to define or limit the scope of the invention.

Turning now to the specific embodiments of the invention selected for illustration in the drawings, there is shown apparatus for making hollow concrete panels comprising a bed 11 enclosed by upright end members 12 and side members 13, each end member 12 having a series of openings 14 formed therein, and a plurality of collapsible mold cores 15 adapted to be received by openings 14 and held in position thereby during the pouring of concrete.

Referring to the embodiment of the invention shown in FIGS. [-7, each collapsible mold core 15 comprises a pair of top wall units 16, 17 joined together along their abutting edges by a central hinge 18, side wall units 21, 22 abutting the outer edges of top units 16, 17 and joined thereto by hinges 23, 24, respectively, and means including a hydraulic jack 25 connected between side wall units 21, 22 for moving them about hinges 23, 24 and for moving top units 16, 17 about their central hinge 18.

Means, including links'26-28, are provided for limiting movement of the side wall units 21 and 22 about hinges 23, 24, and for limiting movement of top units 16,17, about central hinge 18.

Hinges 18 and 23, 24 are preferably full length piano-type hinges.

Top unit 16 includes a top wall 31 having a substantially U-shaped sheet metal member 32 welded thereto with stiffening being provided by webs 33 spaced along its length. A portion of each web 33 is contained within U-shaped member 32 to form bulkheads 34 at spaced intervals.

Top unit 17 is constructed in similar fashion, and is provided with a top wall 35, U-shaped sheet metal member 36, and webs 37 having a portion contained within U-shaped member 36 to form bulkheads 38 at spaced intervals along the length of unit 17.

Side wall unit 21 includes a side wall 41 with a top horizontal section 42, a bottom slant section 43, a bottom horizontal section 44, and a bottom upward slant section 45. A groove 46 is formed in bottom slant section 43 and contains a pneumatic rubber tube seal 47 which seals the bottom of the mold core to prevent concrete from flowing under core into the interior thereof. Side wall 41 is stiffened along its length by gussets 52, 52 which have a pin 53 mounted thereon.

Side wall unit 22 is of similar construction as unit 21, and is provided with side wall 54, top horizontal section 55, bottom slant section 56 (having groove 57 and resilient seal 58), bottom horizontal section 61, bottom upward slant section 62, and strengthening gussetts 63 and 64 which support a pin 65.

To move the elements of mold core 15 into its open position, hydraulic jacks 25 are connected between a number of the gussets 52 and 64 by pin 53 (which is connected to piston rod 68 of hydraulic jack 25), and pin 65 (which is connected to the cylinder of jack 25 by connecting bar 72). Each hydraulic jack 25 is supplied with hydraulic fluid through couplings 73a, 74a, valves 73b, 74b, supply lines 73, 74, and connecting hoses 75 and 76.

To eliminate voids in the concrete between cores 15, a number of vibrators 77 are mounted on the inside of side walls 41 and 54 and are air-operated, the air being supplied through air line 81 and connecting hoses 82,

Movement of the wall elements about hinges 18 and 23, 24 is limited by links 26-28. Link 26 is provided with a slot 91 at one end which receives pin 53 of side wall unit 21 and has its other end connected to web 33 of top unit 16 by a pin 92. Accordingly, slot 91 restricts the movement of side unit 21 toward and away from top unit 16 about hinge 23.

Similarly, link 28 is provided with a slot 93 which is received by pin 65 of side wall unit 22 and has its other end connected to web 37 by a pin 94. Movement of side wall unit 22 toward and away from top wall unit 17 about hinge 24 is limited by slot 93.

Link 27 is provided with a slot 95 which receives pin 94 to connect link 27 to web 37 of top wall unit 17, and link 27 has its other end connected to web 33 of top wall unit 16 by pin 92. Accordingly, movement of top wall units 16, 17 about their hinge 18 is limited by slot 95.

In operation, mold core 15 is made to assume its open position by supplying the jacks 25 with hydraulic fluid to move the piston rods 68 outwardly, with links 26-28 acting to limit the extent of the movement of the elements around hinges 18 and 23, 24. Hydraulic supply to lines 73 and 74 is cut off by closing valves 73b and 74b, and mold core 15 is then disengaged from the source of hydraulic fluid by uncoupling the couplings 73a and 74a. Mold core 15 is now a completely independent unit which may be moved into any desired position, and it is held in open position, throughout the panel making process, by the hydraulic fluid trapped in lines 73 and 74 and jacks 25.

Lower concrete layer 101 is poured onto bed 11 of the mold formed by upright side members 13 and end members 12, and a series of mounds 102 having a lower portion 103 of a web are formed (by moving a plowlike device through the upper portion of concrete layer 101.) to define a series of parallel troughs 104.

The concrete is allowed to partly set until it has hardened sufficiently to support the weight of mold cores 15, which are then placed in each trough 104. The ends of mold cores 15 are received in openings 14 in end members 12 of the mold form and are held in place thereby. The bottoms of mold cores 15 are sealed against the admission of fresh concrete by seals 47 and 58. An upper concrete layer 105 is poured and connects with the lower portion 103 of the webs on top of mounds 102 of lower layer 101.

Vibrators 77 are actuated to vibrate the concrete between cores 15 and eliminate any voids therein, and the concrete is set and hardened.

Then the mold cores 15 are removed from the concrete panels by peeling side walls 41 and 54 and top walls 31 and 35 from the concrete. This is accomplished by reversing the action of hydraulic jack 25 to pull the side wall units 21 and 22 toward each other. Side walls 41 and 54 are made of flexible material and the force from hydraulic jacks 25 starts the peeling action at the bottom to free first the lower part of side walls 41 and 54 and then progress upwardly until the entire side wall is peeled away.

Side walls 41 and 54 having been completely peeled away from the concrete, pin 53 of side wall unit 21 is pressing against the inner end of slot 91 in link 26, and pin 65 of side wall unit 22 is pressing against the inner end of slot 93 in link 28. These forces are transmitted by link 26 to pin 92 of top wall unit 16, and by link 28 to pin 94 of top wall unit 17. Accordingly, top units 16 and 17 are moved toward each other about hinge 18 to peel top walls 31 and 35 away from the concrete until pin 94 makes contact with the inner end of slot in link 27. This position of the mechanism is shown in FIG. 5 and represents the collapsed condition of mold cores 15. in this position, cores 15 are removed from the hollow concrete panel.

It is to be noted that top wall units 16 and 17 are preferably made of monocoque construction so as to obtain torsional rigidity.

Mounds 102 and lower portion 103 of the concrete web are allowed to set until they have enough firmness to support the mold cores without breaking the surface of the lower concrete layer 101, and the troughs 104 help to properly position the mold cores 15. The mounds 102 are slightly deformed by the impression of the seals 47 and 58 which press into the concrete. Troughs 104 help in aligning mold cores 15 and in keeping them in alignment.

Upper concrete layer 105 is poured directly on top of the mold cores 15, and this aids in keeping the mold cores 15 finnly seated.

It is to be understood that, for the sake of clarity, no reference has been made to the reinforcement wires or bars, prertensioned or post-tensioned, which are normally used in the manufacture of concrete products. If desired, the outer surfaces of the cores may be given a coating of oil to inhibit sticking to the concrete.

FIGS. 8-10 disclose a modified form of the apparatus in which the outer walls ofa mold core 111 are formed integrally of flexible sheet metal. Mold core 111 is shown as being more rectangular in shape than mold core 15, but it operates in the same manner, as is shown in FIGS. 9 and 10. Side walls 112 peel away from the concrete, the bottom of side walls 112 peeling first and progressing upwardly until side walls 112 are completely withdrawn from the concrete. Top walls 113, 114 peel away from the concrete starting at their outer edges and progressing toward center line 115.

Mold core 111 is provided with resilient seals 116 (which prevent liquid concrete from flowing beneath the core), U-shaped members 117, webs 118, gussets 121, and hydraulic jacks 122 connected to pins 123 mounted on gussets 121. Slotted links 124-126, with their associated pins 123 and 127 (mounted on webs 118), limit the movement of walls 112114. Lines 128 and connecting hoses 131 supply hydraulic fluid to jacks 122, and line 132 and connecting hoses 133 supply air to the vibrators mounted on the inside of side walls 112.

It is to be understood that the form of the invention herewith shown and described is to be taken as a presently preferred embodiment. Various changes may be made in the shape, size and arrangement of parts. For example, equivalent elements may be substituted for those illustrated and described herein, parts may be reversed, and certain features of the invention may be utilized independently of the use of other features, all without departing from the spirit or scope of the invention as defined in the subjoined claims.

What is claimed is:

1. A method of making hollow concrete panels comprising pouring a lower concrete layer, placing thereon a hollow mold core including a top wall and aide walls and an open bottom defined by edges, wherein said top wall has side edges and a center line, sealing along the edges of the open bottom to prevent fresh concrete from entering the said open bottom and locking the core in place, pouring an upper concrete layer connecting with said lower layer, allowing the concrete to set, collapsing the core by first peeling said side walls from the concrete from the bottom up and then peeling the top wall from the concrete starting at the side edges and progressing toward the center line of the top wall, and removing the core from the concrete.

2. The method of claim 1 including allowing the concrete of said lower layer to partly set, pouring the upper concrete layer so that it connects with the lower layer, and setting and hardening the concrete, whereby the upper concrete layer bonds to the lower layer and both layers complete the cure as one cast.

3. The method of claim 1 including the steps of forming a series of mounds in said lower concrete layer to define troughs, and placing a mold core in each trough.

4. The method of claim 1 including the step of vibrate rht satsssrsisis i nssrn ss sssizraon the edges includes placing gaskets along the edges and pouring concrete on top of the core to press the gaskets against the bottom to prevent fresh concrete from entering said open bottom and locking the core in place. 

1. A method of making hollow concrete panels comprising pouring a lower concrete layer, placing thereon a hollow mold core including a top wall and aide walls and an open bottom defined by edges, wherein said top wall has side edges and a center line, sealing along the edges of the open bottom to prevent fresh concrete from entering the said open bottom and locking the core in place, pouring an upper concrete layer connecting with said lower layer, allowing the concrete to set, collapsing the core by first peeling said side walls from the concrete from the bottom up and then peeling the top wall from the concrete starting at the side edges and progressing toward the center line of the top wall, and removing the core from the concrete.
 2. The method of claim 1 including allowing the concrete of said lower layer to partly set, pouring the upper concrete layer so that it connects with the lower layer, and setting and hardening the concrete, whereby the upper concrete layer bonds to the lower layer and both layers complete the cure as one cast.
 3. The method of claim 1 including the steps of forming a series of mounds in said lower concrete layer to define troughs, and placing a mold core in each trough.
 4. The method of claim 1 including the step of vibrating the poured concrete to eliminate voids therein.
 5. The method of claim 1 wherein said sealing along the edges includes placing gaskets along the edges and pouring concrete on top of the core to press the gaskets against the bottom to prevent fresh concrete from entering said open bottom and locking the core in place. 